Abstract: A process for treating an alumina monohydrate-based bauxite by high temperature caustic digestion includes the steps of introducing alumina trihydrate into the digested slurry at a temperature of less than 200° C., in order to obtain an aluminate liquor at atmospheric pressure having an alumina/caustic weight ratio between 1.20 and 1.30, and diluting the resultant aluminate liquor to result in a caustic concentration between 160 and 175 g Na2O/liter. After settling and filtration, the resulting supersaturated liquor undergoes a further dilution before or during a crystallization step. The alumina trihydrate product is filtered from the spent liquor, which is concentrated and recycled.

Abstract: A method is disclosed for controlling the precipitation of soluble sodium oxalate in Bayer process liquor which comprises adding a surface active quaternary ammonium compound to the Bayer process liquor and then subsequently adding a mixture of a hydrophobic oil and at least one surfactant.

Abstract: This invention relates to a process for removing sulphates and calcium from a water stream which includes the steps of: combining the water stream and an amount of amorphous aluminum trihydroxide (Al(OH)3); allowing the formation of ettringite (3CaO.Al2O3.3CaSO4.31/32H2O) as a precipitate; and removing the precipitated ettringite from the water stream.

Abstract: Process for treating alumina monohydrate-based bauxite by high-temperature caustic digestion characterized in the following series of operations:

Abstract: A process for preparing a nanocrystalline material comprising at least a first ion and at least a second ion different from the first ion, and wherein at least the first ion is a metal ion, is described. The process comprises contacting a metal complex comprising the first ion and the second ion with a dispersing medium suitable to form the nanocrystalline material and wherein the dispersing medium is at a temperature to allow formation by pyrolysis of the nanocrystalline material when contacted with the metal complex.

Abstract: The present invention comprises a method for reducing the viscosity of the settled mud or underflow of a raked thickener thereby reducing the torque necessary to move the rake blade through the settled mud. The method includes the step of delivering a viscosity modifier to the settled mud and in front of the rake blade by pumping the viscosity modifier down the rake arm to an area in front of the rake blade. The method also includes an improved rake mechanism that includes a means for delivering viscosity modifier to the settled mud and in front of the rake blade. The present invention also includes a method for increasing the rate of consolidation of flocculated solids in a slurry.

Abstract: A process of recovering alumina from a pregnant Bayer process liquor by crystallisation after adding to the liquor a crystallisation modifier characterised in that the crystallisation modifier comprises: (a) a polyalkoxylated non-ionic surfactant, (b) a surfactant, or precursor thereof, which is not a polyalkoxylated non-ionic surfactant and (c) water. In a further aspect of the invention the composition may contain water but preferably contains substantially no water. Preferred compositions for the crystallisation modifier for use in this process contain a surfactant blend which consists essentially only of the polyalkoxylated non-ionic surfactant (a) and the surfactant (b) or precursor thereof. The process consistently gives excellent improvement in crystal size without decreased yield. Specifically the process results in a reduction in the percentage of undersized crystals.

Abstract: The present invention is directed to improvements in the Bayer mining process, used for the recovery of alumina from bauxite ore. Water-continuous emulsion polymers are advantageously used to improve the clarification, filtration and scale control of red-mud containing liquors generated during the Bayer process. Preferred polymers are high molecular weight poly(methyl acrylate/acrylic acid), poly(methyl acrylate), poly(vinyl acetate/acrylic acid/methyl acrylate) and a combination of a high molecular weight poly(methyl acrylate/acrylic acid) with a lower molecular weight poly(methyl acrylate/acrylic acid).

Abstract: A process for reducing the level of colloidal iron in a Bayer process stream comprises intermixing an amidoxime polymer with a Bayer process stream and separating the resultant polymer-iron complex to provide purified sodium aluminate solution.

Abstract: A method for producing an indium oxide-tin oxide powder, which comprises supplying to react an aqueous solution of an indium salt, an aqueous solution of a tin salt and an aqueous alkaline solution into water at 40.degree. C. or more and less than 100.degree. C. so that the pH during the reaction is maintained within the range from 4 to 6, forming a precipitate, washing the formed precipitate after solid-liquid separation, and calcining the precipitate at 600.degree. C. or more and 1300.degree. C. or less.

Abstract: The present invention is directed to the clarification of red mud-containing liquors generated in the Bayer process for the recovery of alumina from bauxite ore with a combination of high molecular weight emulsion polymer and lower molecular weight emulsion polymers. The invention is also a method for the same purpose utilizing a methyl acrylate emulsion homopolymer.

Abstract: Processes for spray drying water-soluble and water-swellable vinyl-addition polymer-containing dispersions, emulsions and microemulsions to obtain substantially dry water-soluble or water-swellable polymer particles, compositions of substantially dry water-soluble or water-swellable polymer particles, methods of agglomerating spray-dried polymer particles, and methods of using spray-dried polymer particles and agglomerates in water-treating, mining, paper, food processing, soil conditioning, solution thickening, biotechnological, and oil recovery applications are disclosed.

Abstract: A method for improving the flocculation of suspended solids in a Bayer process liquor in a primary settler stage. The method includes the step of adding to a primary settler feed a composition including water-continuous polymer, said polymer being hydrolyzable in a Bayer process liquor to an acid form, said acid form being an active red mud flocculent. A novel emulsion, and a polymerization technique for obtaining high molecular weight emulsions are also disclosed.

Abstract: The recovery of aluminum chloride from deactivated alkylation catalyst complexes by hydrogenation using hydrogen gas and an aluminum catalyst is disclosed. Using aluminum to catalyze the hydrogenation allows the reaction to proceed at a lower temperature and pressure while reducing the amount of hydrogen chloride present in the reactor thus reducing the corrosiveness and cost of the aluminum chloride recovery. Methods for batch, batchwise continuous, and continuous aluminum chloride recovery are disclosed.

Abstract: Processes for improving solids/liquids separation efficiency in the Bayer process are disclosed, wherein solids are flocculated with hydroxamated polymers and centrifuged.

Abstract: The invention relates to a method for the treatment of an impure aluminium oxide so that the organic impurities present therein it are converted into an insoluble and easily separable substance. According to the invention, aluminium oxide which contains organic matter as impurities is finely ground, the finely ground aluminium oxide is dissolved at an elevated temperature in sulphuric acid which has a concentration of at minimum 90% by weight, the amount of the sulphuric acid being at least stoichiometric in relation to the amount of aluminium oxide, the organic matter being carbonized into an insoluble and easily separable substance, and, if desired, the obtained mixture is treated further in order to form a solution-form or solid chemical which contains aluminium.

Abstract: A new and improved method for inhibiting the precipitation of sodium oxalate crystals in a Bayer process liquor is provided. In an embodiment, the method comprises the step of adding to the Bayer process liquor, after red mud separation, a minor effective amount of a liquor oxalate stabilizer selected from hydrocarbon-substituted amine oxide compounds and/or hydrocarbon-substituted betaine compounds.

Abstract: A process for alkaline leaching of a titaniferous material containing silica and alumina impurities in which spent leachant is recycled by treating to remove the silica and alumina impurities therefrom, by heating, maintaining the leachant at leaching temperature, or treating with an additive. The removal of the silica and alumina impurities by the method of the invention enables further use of the leachant.

Abstract: Process for the production of aluminium hydroxide by digesting bauxite with alkali solution and precipitating aluminium hydroxide from the digestion solution, comprising:a combining bauxite and alkali solution having a caustic concentration of at least 180 grams per liter expressed as sodium carbonate and digesting partly the bauxite in the combined product in a first digestion step at relatively low temperature,b separating reaction product obtained in step a into a liquid phase and a solids/liquid slurry,c combining liquid phase and solids/liquid slurry obtained in step b and digesting the combined product in a second digestion step at relatively high temperature,d releasing heat from the reaction product obtained in step c to preheat liquid phase obtained in step b,e separating the reaction product obtained in step d into a supersaturated sodium aluminate solution and undissolved material,f precipitating aluminium hydroxide from the supersaturated sodium aluminate solution obtained in step e and separating

Abstract: Processes for improving solids/liquids separation efficiency in the Bayer process are disclosed, wherein Bayer process streams are treated with calcium or magnesium salts, flocculated with carboxylic acid or salt group-containing polymers, and centrifuged.

Abstract: A method for flocculation of red mud in Bayer Process streams utilizing a fatty acid or fatty acid ester free latex polymer flocculant. Preferred fatty acid free emulsifiers useful for the preparation of such flocculants are obtained by reacting ethylene and/or propylene oxide with a reagent selected from the group consisting of ethylene diamine, ethanol and ethylene glycol.

Abstract: A process for the treatment of aqueous acidic liquors containing dissolved aluminum and/or iron compounds to produce an aluminum and/or iron sulfate water-treatment product is characterized by the combination of steps comprising contacting the liquor with a basic material capable of reacting with the dissolved aluminum and/or iron compound to precipitate aluminum and/or iron values, separating the precipitate in the form of a cake or slurry from the remaining liquor, treating the cake or slurry with sulfuric acid to re-dissolve aluminum and/or iron values and to produce a solution of aluminum and/or iron sulfate and separating suspended solid matter from the solution. The liquor may be a waste product from industrial processes or may be a mine effluent and the process avoids the need to dispose of these to waste.

Abstract: An electro-conductive oxide particle comprising indium atoms, antimony atoms and oxygen atoms in a molar ratio of In:Sb:O being 1:0.02-1.25:1.55-4.63 and having a primary particle diameter of from 5 to 500 nm.

Abstract: The processing of bauxite in the Bayer Process results in the formation of titanaceous, siliceous, and other scale on equipment and apparatus such that a great deal of time and effort is spent in order to maintain the process at its height efficiency by reducing or eliminating the same. The scale is treated, reduced, altered, etc., according to the present invention by the use of hydroxamated polymers having weight average molecular weights ranging from about 1,000 to less than about 10,000.

Abstract: The processing of bauxite in the Bayer Process results in the formation of titanaceous, siliceous, and other scale on equipment and apparatus such that a great deal of time and effort is spent in order to maintain the process at its height efficiency by reducing or eliminating the same. The scale is treated, reduced, altered, etc., according to the present invention by the use of hydroxamated polymers having weight average molecular weights of over about 10,000.

Abstract: Sodium oxalate is precipitated from spent Bayer process liquor by mixture with a low total alkalinity (TA) sodium oxalate seed solution that has been treated with two or more adsorbents to remove organic poisons from the sodium oxalate. The adsorbents are preferably two different adsorbents selected from activated carbon, ESP dust, calcium oxide and magnesium oxide. Surprisingly, combination treatments with activated carbon and ESP dust are most effective even though ESP dust alone has little effect on oxalate removal.

Abstract: In the Bayer process for producing alumina from bauxite of the type wherein the bauxite is added to a caustic solution to produce a soluble aluminate solution and an insoluble red mud fraction which is then subjected to one or more separation steps to produce a thickener overflow which is then subjected to a Sand Filter to polish the thickener overflow the improvement which comprises treating the thickener overflow with a solids removal efficiency improving amount of a biopolymer.

Abstract: An aqueous suspension of coagulatable material is coagulated by adding polymeric coagulant to the suspension and then separating the resultant coagulated material from the liquor. The coagulatable material may be present in the aqueous suspension as a suspension of suspended solids or as colloidally dispersed solids. The suspension may be coal tailings or other aqueous (generally mineral) suspension. The polymeric material must be a low molecular weight, highly ionic, polymeric material formed from a diallyl dialkyl ammonium salt. It is added to the aqueous suspension while in the form of polymeric particles having a size mainly above 30 .mu.m and that will dissolve into the suspension and coagulate the coagulatable material. An anionic high molecular weight, flocculant is generally added subsequently in order to flocculate the coagulated material.

Abstract: Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulphur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described.

Abstract: Processes for reducing the level of impurities in alumina trihydrate produced in the Bayer process are disclosed, wherein alumina trihydrate-containing process streams are flocculated with hydroxamated polymers and centrifuged.

Abstract: A process is disclosed for treating used aluminum chlorofluoride catalyst either alone or mixed with organics. It involves forming a solution of the catalyst in water or an aqueous acid and then adjusting the pH and/or composition of the aqueous phase formed to precipitate compounds containing the aluminum and/or fluorine.

Abstract: Improved process for fluidifying flocculated aqueous suspensions of red muds in the production of alumina from bauxite by the Bayer process, which consists:in dissolving bauxite using sodium hydroxide;then, in decanting and in washing the red muds formed in order to separate them from the alumina in successive vats, while recycling the washing waters upstream;and finally, in eliminating the red muds thus treated;and in which a flocculant (F) consisting of a polyacrylamide of molecular weight greater than ten million is introduced into the suspension of one of the successive vats;wherein a dispersing agent (D) formed by an anionic acrylic acid polymer of molecular weight lower than fifty thousand is added simultaneously with said flocculant (F) to the suspension in the same vat.

Abstract: There is disclosed a method for improving the brightness level of aluminum hydroxide removed from a caustic solution. The method comprises:(a) pre-filtering the solution to remove contaminants therefrom; and (b) contacting the filtered solution with an adsorbent consisting essentially of a calcined compound having the formula: A.sub.w B.sub.x (OH).sub.y C.sub.z.nH.sub.2 O wherein A represents a divalent metal cation selected from the group consisting of: Mg.sup.2+, Ni.sup.2+, Fe.sup.2+, Ca.sub.2+ and Zn.sup.2+ ; B represents a trivalent metal cation selected from the group consisting of: Al.sup.3+, Fe.sup.3+ and Cu.sup.3+ ; C represents a mono- to tetravalent anion selected from the group consisting of: OH.sup.-, Cl.sup.-, Br.sup.-, NO.sub.3.sup.- CH.sub.3 COO.sup.-, C.sub.2 O.sub.4.sup.2-, CO.sub.3.sup.2-, SO.sub.4.sup.2-, PO.sub.4.sup.3-, Fe(CN).sub.6.sup.3- and Fe(CN).sub.6.sup.4- ; and w, x, y, z and n satisfy the following: 0<z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq. 1/2 y and 12.gtoreq.n.gtoreq.

Abstract: The filtration rate of Bayer Process primary settler overflow and/or the flocculation in the initial stages of the washer train in the Bayer Process are improved by contacting the settler feed stream or the feed stream to the first stages of the washer train first with a) a lower molecular weight polymer which contains hydroxamic acid and/or salt groups and then with b) a mixture of an anionic polymer and a second, higher molecular weight polymer which contains hydroxamic acid groups.

Abstract: Aluminum and fluorine are recovered from fluorine containing waste materials from the production of aluminum metal (FCWM) as ALF.sub.2 OH hydrate by a process comprising: leaching FCWM with dilute sulphuric acid at a pH value within the range of 0-3; if needed adding aluminum in an acid soluble form; adjusting the pH value of the aqueous phase to a value within the range 3.7-4.1 at the end of the leaching period by addition of a caustic aqueous solution; precipitating silica at a temperature not exceeding 60.degree. C.; separating the reaction mixture into a solid phase containing precipitated silica and non-soluble residues of the FCWM and a purified solution; and precipitating AlF.sub.2 OH hydrate from the purified solution at a temperature within the range 90.degree.-100.degree. C. and at a pH value not exceeding about 4.1 by controlled continuous addition of an aqueous caustic solution. Reducing and/or non-oxidizing operating conditions are maintained during all these process steps. The precipitated AlF.

Abstract: A process for the production of aluminum hydroxide from an alumina-containing ore comprising, in a process for the production of aluminum hydroxide involving extraction of alumina from an alumina-containing ore by an aqueous alkaline solution, supplying a slurry containing the alumina-containing ore at a high solid content which is prepared from a small amount of an alkaline solution together with an aqueous alkaline solution which is so preheated to a temperature that a preheated temperature is enough high to have a temperature after the mixing with the slurry which is higher than an extraction temperature of alumina, simultaneously or after the mixing them, to an extraction apparatus comprising of a tube reactor, extracting alumina from the alumina-containing ore under extraction conditions of a temperature of 120.degree.-160.degree. C.

Abstract: The process for separating U or Th values from values of at least one other metal such as Ta, Nb, Sc, Zr, Ti or Mg, wherein all of the values are contained in a difficult soluble matrix of highly fluorinated feed materials such as U or Th bearing ores or the processing products, processing intermediates, or processing residues thereof, the method comprising the steps of:(a) digesting the feed materials with an aqueous, mineral acid, digest medium containing one or more complexing materials such as H.sub.3 BO.sub.3, or ions of group 2A, 3A, 4A, 5A, 6A, or 7A metals, Fe, B, Al or Si;(b) maintaining the temperature of the medium between about 55.degree. C. and about 85.degree. C.

Abstract: Water soluble polymer flocculants are formed from monomers derived from ethylenically unsaturated dibasic carboxylic acids of formula (I) where R.sup.1 =H and R.sup.2 =COOH or R.sup.1 =COOH and R.sup.2 =H. Flocculants are provided for use in Bayer process liquors which are copolymers of acids of formula (I) with ethylenically unsaturated copolymerisable monomer and which have molecular weight above 300,000. Preferably the polymer is a terpolymer of dibasic acid, monobasic and polymerisable termonomer. A particularly preferred flocculant is formed from at least 10 mol % maleic acid with acrylic acid and acrylamide as comonomers and is used preferably for flocculation of red mud in the primary settler and/or the various red mud washing stages.

Abstract: A composition comprising a blend of an inverse emulsion of a hydroxamated polymer and a second inverse emulsion of a second polymer selected from the group consisting of alkali metal (meth)acrylate homopolymers, ammonium (meth)acrylate homopolymers, and copolymers of the (meth)acrylates with (alk)acrylamides, wherein the molar ratio of hydroxamated polymer to said second polymer in the emulsion is within the range of about 99:1 to 15:85 when the second polymer is an alkali metal (meth)acrylate homopolymer or copolymer and is within the range of about 99:1 to 58:42 when said second polymer is an ammonium (meth)acrylate homopolymer or copolymer. Processes for removing suspended solids from Bayer alumina process streams using these compositions are also provided.

Abstract: Metals contained in various wastewaters are selectively recovered as metal precipitates and/or as spinel ferrite and water suitable for discharge into the environment is obtained. High grade magnetic spinel ferrite is recovered from wastewaters having aluminum and arsenic if present in the wastewater, removed from the wastewater. There are three process stages for the treatment of wastewater. In the first process stage which is optional, at least a portion of at least one non-ferrous or non-ferric metal is precipitated from the wastewater by subjecting the wastewater to an oxidizing agent to increase the oxidation-reduction potential of the water, by adjusting the pH of the wastewater to a pH at which the metal precipitates from the water and by adding an organic or inorganic sulfur compound, capable of causing the metal to form a precipitate, to the water in a quantity sufficient to precipitate the metal.

Abstract: Alginic acid is used in combination with high molecular weight synthetic water soluble polymers to flocculate red mud from Bayer process liquors. Superior clarity of supernatant liquor is achieved using the process of the invention.

Abstract: Aqueous wood treating compositions, containing compounds which contain elements selected from copper, chromium and arsenic and oxyalkylene polymer additives, provide improved stability to CCA solutions containing additives. In addition, the compositions of the present invention have been found to retard hardening effects associated with wood treated with commercial CCA solutions.

Abstract: The use of a dewatering aid comprising a sulfosuccinate and an oil in the filtration of alumina trihydrate is disclosed.

Abstract: A process for preparing an ultra-white alumina trihydrate having a G.E. brightness of at least about 98%. The product is alumina trihydrate that has been rehydrated with coprecipitation, and the crystal phase of the product is primarily gibbsite in thin platelet form having a ratio of thickness to diameter of about 0.2 to about 0.3. The product is prepared by flash activation of a white initial alumina trihydrate, addition of the activated material to a purified sodium aluminate liquor having an alumina to caustic ratio of about 0.5, and rehydrating and precipitating the alumina at ambient temperature under agitation for about 48 hours, followed by washing and drying of the resulting precipitate. The material is especially useful as a filler or coating in papermaking, and it can be substituted for a portion of titanium dioxide pigment in the ratio of 1:1, and can be combined with titanium dioxide as a pigment mixture, either in slurry form or in dry form.

Abstract: A method of manufacture including bringing seed and aluminum hydroxide together in an aqueous medium and hydrothermally digesting for producing boehmite at the expense of the aluminum hydroxide is described. Also disclosed is a process for forming a ceramic body from colloidal boehmite and alpha alumina. Alpha alumina is added to ultimately produce a seeded gel containing microcrystalline boehmite, the seeded gel capable of being sintered at a low temperature to produce a ceramic product. The colloidal boehmite may be purified by ion exchange to remove alkali metal ions.

Abstract: A process for treating an AB.sub.5 Ni--MH battery to recover purified positive and negative electrode components of the battery is disclosed. An AB.sub.5 Ni--MH battery is placed in a mineral acid leach solution to cause the positive and negative electrode components of the battery to separate. The positive and negative electrode components are maintained in the leach solution until the negative electrode component breaks down into its dissolved rare earth metal constituents and metallic solids. The metallic solids remaining from the negative electrode component and the positive electrode components are separated from the mineral acid leach solution and subjected to an elutriation process and thereafter to ball milling to obtain Ni rich powder and Fe. The mineral acid leach solution containing the completely dissolved rare earth metals is subjected to a phosphate precipitation process to recover La and Ce in precipitate, and then subjected to a second precipitation process to recover Ni, Co, Mn and Al.

Abstract: Organic impurities are removed from Bayer process liquors using a polymer which contains vinylamine and/or vinylformamide.

Abstract: An lithium aluminum complex hydroxide salt (LAHS) and a process for preparation thereof is provided. The LAHS is represented by the formula;(Al.sub.2 Li(OH).sub.6).sub.n X, mH.sub.2 Owherein X is an inorganic or organic anion, n is a value number of X, and m is a number of not more than 3, and having an orientation degree (OD) of not less than 10, OD being defined by the formula;OD=I.sub.(002) /I.sub.(110)wherein I.sub.(002) is a relative intensity of a peak in X-ray diffraction pattern with an index of a plane (002) appearing at a spacing (d) of 7.67 .ANG. to 7.84 .ANG. and I.sub.(110) is a relative intensity of a peak in X-ray pattern with an index of a plane (110) appearing at a spacing (d) of 4.41 .ANG. to 4.45 .ANG.. This LAHS is useful for a stabilizer for chlorine-containing polymers or olefin-type resins containing halogen-containing catalyst residues.

Abstract: Siliceous materials produced by thermally treating spent Bayer process liquors are obtained in modified form when produced in the presence of polymeric quaternary ammonium compounds, polyamine polymers, copolymers of acrylic acid and acrylamide, and polyacrylamides. These modified siliceous materials possess morphologies which confer upon them a reduced tendency to deposit on surfaces throughout the process.

Abstract: There is disclosed an amorphous, polymeric material that contains phosphorous, aluminum and carbon atoms, and that is the reaction product of a buffered liquid mixture of a source of phosphorous, such as 85% phosphoric acid, a source of aluminum, such as boehmite, and an organic liquid buffer, such as a carboxylic acid. The polymeric material may be converted to a glassy or crystalline solid by heating to a temperature of at least 150.degree. C., and may be cellulated.